DE10113801A1 - Device for controlling at least one capacitive actuator and method for operating such a device - Google Patents

Abstract

A device for driving at least one capacitive positioning/adjusting element (P1...Pn) has a charge capacitor (C1) which can be charged by a power source to a given voltage relative to a reference potential (GDN). A series circuit of the primary winding of a transformer (Tr) and the parallel circuit of a first controlled switch (S1) and a first diode (D1) is connected across the charging capacitor (C1).The point of connection of the transformer secondary winding (w2) and the capacitive adjusting/positioning element (P1...Pn) is joined via a switching device (S3) to a power source (B) e.g. a motor vehicle battery. An Independent claim is given for a method of driving a device.

Description

The invention relates at least to a device for actuation tens of a capacitive actuator, especially for a Fuel injection valve of an internal combustion engine, with a from an energy source to one with respect to a reference point tials predetermined voltage chargeable charging capacitor, wherein parallel to the charging capacitor, the series circuit from the Primary coil of a transformer and the parallel connection a first controllable switch and a first diode is connected, the series connection from the secondary coil of the transformer and the parallel connection of one second controllable switch and a second diode pa parallel to the capacitive actuator or in the case of several Actuators of the series connections each made of a capacitive Actuator and a selection switch assigned to it is switched and the first switch, the second scarf ter and the selector switches from a control circuit such can be controlled that the voltage at the capacitive control member and / or the current through the capacitive actuator a predetermined value is regulated. The invention relates also a method for operating such a device tung.

Such a device is described in P 19944733.0. This device works on the flyback principle which first by closing the first switch energy from Charging capacitor fed via the primary coil in the transformer is saved. After the first switch was opened again the stored energy flows through the secondary coil the second diode to the capacitive actuator or in the case of several Actuators to the actuator that by closing the off selector switch was selected.  

The described transfer of charge from the charging capacitor to the capacitive actuator takes place successively through periodi Close and open the first switch. after the If the desired voltage is reached on the actuator, it remains for a desired time in which e.g. B. through the injector the actuator should remain open.

Then the second switch is closed, so that the im Actuator stored energy back into the Trans formator flows to from there after opening the second Switch over the primary coil and the first diode back to Charging capacitor to flow. Unloading also takes place successively sive by periodically closing and opening the second Switch.

The charging and discharging times are controlled by a control circuit regulated, the one hand measured values of the currents through the scarf ter are supplied and on the other hand the switch Controls pulse width modulated signals.

By transferring charge from the charging capacitor to the kapa citative actuator and the associated transformation from electrical to magnetic energy and step back avoidable losses, so that the charging capacitor slowly discharges. The one described in P 19944733.0 Device is the charging capacitor by a switching power supply reloaded again, but the not insignificant costs ver ursacht.

The object of the invention is therefore a device and specify a method that is less expensive.

The object is achieved by a device according to claim 1 and solved a method according to claim 5. Advantageous Next educations are specified in the subclaims.  

The invention makes use of the knowledge that between the charge and discharge cycles for an actuator or at meh other actuators between the cycles of the individual actuators limbs breaks are present that are used to transfer energy from an energy source that can be controlled via a controllable switch tel connected in parallel to the secondary circuit of the transformer can be used. It also becomes the order stood exploited that the flyback converter already out is that it can be operated in both directions. In this way, you can switch to an expensive switching power supply to be dispensed with, since the switching means and the second scarf ter of the control circuit in such a manner according to the invention can be controlled that the charging capacitor at times in which no current through the at least one actuator flows, so if there is no charging or discharging, is charged from the energy source.

The invention is illustrated below with the aid of an embodiment game described with the help of a figure. It shows the

Fig. 1 is a schematic diagram of a device according to the invention.

The device shown in FIG. 1 largely corresponds to the device described in the introduction. So a charging capacitor C1 is connected in series from the primary coil w1 of a transformer Tr, a first switch S1 and a first measuring resistor R1. The first switch S1 and the first measuring resistor R1, a first diode D1 is connected in parallel, the cathode of the diode being connected to the primary coil w1.

The secondary circuit consists of the series connection of the Sekun Därspule w2 of the transformer Tr, a second switch S2 and a second measuring resistor R2, the second scarf ter S2 a second diode D2 is connected in parallel,  that their cathode is also connected to the secondary coil w2 is.

The secondary circuit is created by connecting an An in parallel number of actuators A1. , .An who with a third measurement the status R3 is connected in series, closed. Between the secondary coil w2 and the actuators A1. , .An is still a filter circuit F arranged, the current peaks ausfil should.

The two arrangements of the first and the second measuring resistor stands are marked with the letters a and b, where to be made clear that it is in the case of the different arrangements are two variants, who are equal to each other.

So it would also be possible to replace the first diode D1 only th switch S1 in parallel or the second diode D2 the series connection of the second switch S2 and the two to connect the measuring resistor R2 in parallel. It would also be possible, only a single measuring resistor for both currents paths to use as always at a given time only one of the two current paths is turned on. here based on the circuit variant a could not connected to the secondary coil connection of the second scarf ters S2 with the connection point of the first switch S2 with the first measuring resistor R1, with the second measuring resistor R2 and the second Diode D2 can be connected directly to the ground connection GND could.

Parallel to the series connection from the secondary coil w2, the second switch S2 and the second measuring resistor R2 is in way according to the invention via a switching means S3 giequelle, in particular a motor vehicle battery B, ge on.  

The measuring resistors R1, R2 and R3 are with one inputs Control circuit ST connected depending on the current flow through the respective measuring resistances and the ones to be met Function the switches S1, S2, the switching means S3 and the Selection switch A1. , Pressed on.

As already mentioned in the introduction, a kapa citive actuator P1. , .Pn, which by pressing the assigned neten selection switch A1. , On was selected successively charged by the first switch S1 with a pulsed Signal is controlled.

After a desired period of time during which the voltage on Actuator is kept at the maximum value and during which, for example, that controlled by the actuator The fuel injector is open, the capacitive Discharge actuator by the second switch S2 of the control circuit ST driven with a pulsed signal becomes.

After such a charge / discharge cycle, there is a pause, during which there is no current through the transformer windings or the switches connected in series flow until the next actuator to control, for example, the next Fuel injector loaded and unloaded becomes.

In the manner according to the invention, this pause is now used to the charging capacitor from, for example, the motor vehicle battery reload directly. This is done on the one hand by Closing the switching means S3 the battery B with the second Därspule w2 of the transformer Tr connected and also the second switch S2 by activation with a pulsed sig nal periodically closed and opened to this way To transfer energy from the battery B to the charging capacitor C1 gene.  

In an embodiment of the invention it is also possible to use a diode as switching means S3. However, the actuator P1. , .Pn should only be discharged to the voltage of battery B. This variant is shown in dashed lines in FIG. 1.

By the device according to the invention and the fiction Moderate method of operating the device can be convenient table way in an expensive additional switching power supply to charge the charging capacitor C1.

Claims (7)

1. Device for controlling at least one capacitive actuator (P1... PN), in particular for a fuel injection valve of an internal combustion engine, with a charging capacitor (C1) that can be charged by an energy source to a voltage that is predetermined with respect to a reference potential (GND), parallel to the charging capacitor (C1) is connected in series from the primary coil (w1) of a transformer (Tr) and the parallel circuit of a first controllable switch (S1) and a first diode (D1), the series circuit comprising the secondary coil (w2) Transformer (Tr) and the parallel connection of a second controllable switch ters (S2) and a second diode (D2) parallel to the capacitive actuator (P1.. .Pn) or in the case of several actuators, the series connections each from a capacitive actuator and a selection switch assigned to it (A1... An) is switched and the first switch (S1), the second switch (S2) and the selection switch age (A1. , .An) are controlled by a control circuit (ST) such that the voltage at the capacitive actuator and / or the current through the capacitive actuator is regulated to a predetermined value, characterized in that the connection point between the secondary coil (w2) and the at least one capacitive actuator (P1... PN) is connected via a switching means (S3) to an energy source (B), in particular a battery. 2. Device according to claim 1, characterized in that control the switching means (S3) from the control circuit (ST) bar and in particular a one-way conductor Transistor is. 3. Device according to claim 1, characterized in that the switching means (S3) is a diode.   4. Device according to one of the preceding claims, characterized characterized in that between the first switch (S1) and the Reference potential (GND) a first measuring device (R1) for loading the current through the primary coil (w1) is switched is. 5. Device according to one of the preceding claims, characterized characterized in that between the second switch (S2) and the reference potential (GND) a second measuring device (R2) for Determination of the current through the secondary coil (w2) is. 6. Device according to one of the preceding claims, characterized characterized in that between the one actuator or Connection point of all selection switches (A1 ... An) and the Be tensile potential (GND) a third measuring device (R3) for loading tuning the current through the actuator or the actuator the (P1.. .Pn) is switched. 7. Method for operating a device according to one of the preceding claims, characterized in that the Switching means (S3), in the event that it can be controlled, and the second switch (S2) from the control circuit (ST) in this way can be controlled that the charging capacitor (C1) at times in which no current through the at least one actuator (P1... Pn) flows from which energy source (B) is charged.